Technical Field
Aspects of the present disclosure generally relate to electro-magnetic interference (EMI) shielding, and more particularly, to a method, apparatus, and system for providing EMI shielding that prevents or otherwise inhibits eddy current generation in the shielding.
Introduction
Generally, in order to provide EMI shielding for electronic devices and other items to be shielded from EMI, conductive materials such as copper, aluminum, and steel are used in electronic device enclosures. These enclosures are intended to shield the internal electronics from electro-magnetic noise. However, such enclosures are not suitable for magnetic trackers (either static or dynamic), since any conductive material in or near the magnetic field of a magnetic tracker may distort the magnetic field of the magnetic tracker and result in inaccurate position measurements corresponding to the magnetic tracker. As such, magnetic trackers perform at their best when placed within or near enclosures that are made of non-conductive material only, such as air, glass, or wood.
At least some of such distortion of the magnetic field of the magnetic trackers within conventional EMI enclosures may be due to induced eddy currents. Eddy currents are currents induced in a conductive material when the conductive material is subjected to a changing magnetic field to which the conductive material is exposed. The intensity of the induced eddy currents is proportional to the strength of the applied magnetic field, the electrical conductivity of the conductive material, and the rate of change of the applied magnetic field. Also, the greater the surface area of the conductive material to form multiple current loops within the material, the greater the induced eddy currents.
Once induced by a magnetic field, the eddy currents thereby generated may themselves induce one or more magnetic fields. Therefore, when a magnetic tracker is placed within or near a conventional EMI shield or enclosure, and that enclosure is then subjected to a magnetic field, the eddy currents induced in the conventional EMI shield may result in distortion in the magnetic field measurements of the magnetic tracker, due to magnetic fields generated by the eddy currents. As a result of this distortion, the performance of the magnetic tracker may be diminished.
Accordingly, there exists an unmet need for improved EMI shielding of magnetic trackers.